The restraint systems for passenger protection have been continuously refined since the introduction of airbags. These include, in addition to the front passenger airbag, side impact airbags, and head airbags, also knee airbags and other restraining devices. The evaluation methods used, which make triggering decisions for activating the restraining devices, are generally based on acceleration signals and/or their integrals.
For correct and accurate activation of the restraining devices, the demands on differentiation capability and decision reliability of the data evaluation methods have strongly risen in the past years. In order to meet this rise in demands, acceleration sensors as so-called upfront sensors may be installed in the front section of the vehicle.
A method and a device for triggering passive safety systems are described in the German Patent Application No. DE 101 34 331 C1, for example. The described method makes identification and differentiation of crash severity and crash type possible. In addition, an overlap of an object impacting the vehicle is calculated from the acceleration signals, recorded by sensors, and their simple integrals or from the differences of the simple integrals and the sum of the simple integrals.
A method for protecting passengers of a motor vehicle in the event of an accident is described in German Patent Application No. DE 100 44 918 A1 which analyzes and gates signals from at least two acceleration sensors to ascertain an estimate about the point of impact of an obstacle on the vehicle structure.